1. Field of the Invention
The present invention relates to a communication terminal device using radio and a method for constructing a communication terminal network to be formed as an aggregate of the communication terminal devices, and mainly aims at providing the speech transmission.
2. Description of the Related Art
In the case of carrying out the speech transmission by radio with respect to unspecified many, it is customary to use a high output transmission device that can transmit to a wide ranging area. This is effective when receivers exist in a wide ranging area.
On the other hand, it is also possible to use a transmission device using low power radio. This is generally of a small size and inexpensive, and associated with little restriction regarding the radio wave resources, so that it can be used with ease.
However, the use of the high output transmission device can be problematic regarding the utilization efficiency of the radio band and the energy when the receivers actually do no exist in a wide ranging area.
Also, the transmission device using low power radio is difficult to use with respect to unspecified many because the transmission range is limited to the close distances. It is also impossible to enlarge its range easily when the receivers increased.
Moreover, the speech transmission is unidirectional, and it is difficult to realize the bidirectional transmissions in which arbitrary receiver at arbitrary timing can utter the speech to participate.